Resources/Information for Crank Lubrication?

[Lopez Mike]

But again, what am I to do with this?

I'm not about to buy the book, get the software and redesign my engine. I am building a new hull and really like to take people steaming. Time spent at the computer and in my machine shop is time taken away from steaming. I have any number of friends who are not machinists. They are less equipped to redesign their engines than I am. And even less inclined.

When I first got my engine I checked the opening events for symmetry. More than that would require adjustments that are not on my engine. Nothing I could do about it.

It's a simple little thing. Runs smoothly in both directions. I hook it up as soon as I speed up beyond ticking over. It doesn't seem to gobble up that much wood. I'm quite inclined to take good care of it and leave it alone.

I appreciate that you are likely to improve the 6A. I'm even impressed. But it seems as though there is a message that I should do something.

[Lionel Connell]

You can go crazy chasing "Perfect" with CAD/simulations just to find out the due to the vagaries of the real world you're no better off than if you had stopped at "good enough"

Yes, to and extent this is true, but if you stop before you reach that point, then you don't know if you have made it as good as it could or should be. An engineers job is to lean forward when the real world starts pushing back. The customer or business owners job is to decide when the engineer has gone far enough.

"Good enough" for some, is not always "good enough" for others. In fact, "good enough" for some is a device that barely works, let alone works well, and for some others, "good enough" is seldom realized. The fun is in learning to distinguish the two.

Lionel

[Lionel Connell]

But again, what am I to do with this?

Mike, I did post a reply to your question if you look a few pages up. I detailed some simple measurements that you can take directly off your engine to see if your engine is in the ball park or not. If you do the tests and provide me with your results I will be happy to let you know if I think that any changes may pay dividends.

Alternately, as the song goes, " if your ( engines') happy and you know it clap your hands"

Lionel

P.S. Are we ever going to see some pictures of your new hull?

[cyberbadger]

P.S. Are we ever going to see some pictures of your new hull?

Here Here! It's getting to the point that I'd pay $ to see some Lopez steamboat photos. I think I've seen a trailer....

-CB

[RGSP]

But again, what am I to do with this?
It's a simple little thing. Runs smoothly in both directions. I hook it up as soon as I speed up beyond ticking over. It doesn't seem to gobble up that much wood. I'm quite inclined to take good care of it and leave it alone.

If it ain't broke, don't fix it!

As a side comment, I'm aware of quite a number of steamboaters who use their engines almost exclusively in full forward gear, full reverse, and mid gear sometimes. If you use these points only, valve timing is a lot easier, and indeed I have heard of people using straight Stephenson's links and being happy with the performance. As Lionel says, it's the owners choice on what "good enough" means.

[fredrosse]

From Ron: "The old adage "on paper, an elephant can fly" applies."

Never herd that one before, but for years a common statement was that "an engineer can prove that a bee cannot fly". Well, that just illustrates that the alleged engineer had made incorrect calculations.

In my experience the proper application of the relevant engineering fundamentals, applied correctly, will always give correct answers. The problem with deviation from truth is often because the analysis does not consider all of the relevant fundamentals. A perfect example is found in Ron's statement:

"Timing a steam engine on the bench on air or in a computer simulation and freewheeling will get it close, but it's not going to be optimal. The only way to truly set engine timing is on a prony brake under load and under steam. "

In my opinion, Ron's statement is completely correct, but why does the computer simulation fail to get things completely correct? That is because the computer simulation is probably "half baked", and just identifies the valve timing events. More rigorous analysis here would consider the fluid dynamics of flow/pressure drop as the engine is passing fluid into and out of the cylinder, with continuously variable valve flow area, piston movement, etc.

OK, so the analysis can be made considering the flow dynamics in addition to the simple valve timing events, but why then why does bench testing on air (which inherently applies both valve timing events as well as the fluid dynamics /flow pressure losses) fail to properly simulate the engine's real condition? Yet another set of complicated variables to incorporate into the analysis, the significant amount of heat transfer within each stroke of the engine, plus the inherent steam property of condensation. Anyone who is well acquainted with the design of steam engines knows that this condensation is a major source of losses in steam engines, they knew this very well more than 150 years ago.

So in summary, having valve timing events is very helpful, and certainly necessary in engine design, but it is not the whole story in addressing steam engine performance.

[Lionel Connell]

So in summary, having valve timing events is very helpful, and certainly necessary in engine design, but it is not the whole story in addressing steam engine performance.

The things that I have discussed have been about getting the valve timing working in balance across both ends of the cylinder and across a pair of cylinders in the case of a compound. I.e. I have been talking about the mechanical positions of the valve being the same for both stroke directions across the adjustment range of the expansion link. I have actually not made any statements about this producing the correct timing for a particular application and if this has been missed then people have not been reading vary carefully.

Yes, I agree completely with Fred that working out where the timing events should take place is a completely different subject. But if one does not first understand how to set up the valve gear to work in balance, and how to correctly alter the timing, then knowing where the timing should be set is worthless information.

Lionel

[cyberbadger]

Regarding timing events - I've been reading the last 2 Funnels and enjoying the articles on capturing data via pressure transducers on valve timing by measuring cylinder pressures.

This is only going to become cheaper and easier as time progresses as a modern equivalent to indicator cards.

It's something I'd like to try one day myself - don't know if I'll really get to it anytime soon...

-CB

[DetroiTug]

Quote: "The things that I have discussed have been about getting the valve timing working in balance across both ends of the cylinder and across a pair of cylinders in the case of a compound. I.e. I have been talking about the mechanical positions of the valve being the same for both stroke directions across the adjustment range of the expansion link."

What difference does it make if the valve events are perfectly balanced for each direction of the stroke? because the cylinder/piston arrangement isn't balanced in both directions, nor can it be. The bottom piston face has a void in it's surface area where the piston rod connects. This causes an imbalance in displacement between the upper and lower cylinder and it causes steam engines to lope and there is virtually no way to remedy it. Practically or by worthwhile means anyways.

I appreciate what you're doing and you're giving it the ol' college try which is admirable, but I think you may be overthinking this. If one really wishes to split hairs on this and get it perfect, it's going to go way beyond a simulation in a solids model program. Let's keep it in perspective, we're discussing watercraft that do well to achieve 6 knots under typical pressures ran, one half knot er so up or down isn't going to be deal breaker for anyone. As many, myself included when we bring our I/C background to steam we out of habit focus on the engine, the engine is only a component of the steamplant, the boiler is the most important component, because without a steady and ample output of steam generation, even the most efficient finely tuned engine in the world connected to it is going to be a dog. A slight change there can negate and supersede all the valve work in the world. I would refrain from driving yourself crazy over valve linkage, get your boat launched and then start tuning it as you go. Don't worry, be happy

-Ron

[Lopez Mike]

Poor Tom. All he wanted to find out was crank lubrication stuff. It's like he turned on a faucet and the handle broke off.

I've learned a lot though. But I have a lot to learn. I have a book in front of me about neurophysiology. "Teacher, can I go home now? My brain is full."